X-rays are characterized by very short wavelengths and high frequencies, with wavelengths between about (20~0.06)×10-8 cm. X-rays must therefore be produced by the jumping of an atom between two energy levels of widely differing energies. So the X-ray spectrum is emitted when the electrons in the innermost part of the atom jump, while the optical spectrum is emitted when the electrons in the outer part of the atom jump.X-rays are not deflected in the magnetic field of an electric field. This means that X-rays are a stream of uncharged particles and can therefore produce interference and diffraction phenomena. The X-ray spectrum consists of two parts: the continuous spectrum and the marking spectrum, the marking spectrum overlaps on the continuous spectrum background, the continuous spectrum is due to high-speed electrons blocked by the target pole and the bremsstrahlung radiation, and its short-wave limit λ 0 is determined by the accelerating voltage V: λ 0 = hc / ( ev ) is Planck's constant, e is the electron charge, c is the speed of light in a vacuum. The marker spectrum is composed of a series of line spectra that result from the leaps of electrons in the inner layers of the target element, and each element has a specific set of marker spectra reflecting the structure of the atomic shell. Synchrotron radiation sources produce high-intensity continuous-spectrum X-rays, which have become an important source of X-rays. X-rays are highly penetrating and can pass through many substances that are opaque to visible light, such as inked paper and wood. This invisible rays can make a lot of solid materials visible fluorescence, photographic film sensitivity and air ionization and other effects, the shorter the wavelength of X-rays, the greater the energy, called hard X-rays, wavelength X-rays of lower energy, called soft X-rays. When in a vacuum, high-speed movement of the electron bombardment of the metal target, the target will release X-rays, which is the structure of the X-ray tube principle.